# Specific Domains

**URL:** https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=560

[Latest](https://discourse.julialang.org/latest.md) · [Categories](https://discourse.julialang.org/categories.md) · [Tags](https://discourse.julialang.org/tags.md)

**Page:** 561

---

## [How to speed up AffineExpr generation?](https://discourse.julialang.org/t/how-to-speed-up-affineexpr-generation/3865)

<div class="topic-metadata">

**Author:** [@abulak](https://discourse.julialang.org/u/abulak)\
**Replies:** 9\
**Last updated:** [May 30, 2017, 6:34pm UTC](https://discourse.julialang.org/t/how-to-speed-up-affineexpr-generation/3865 "2017-05-30T18:34:20Z")

</div>

I have a problem with 3000×3000 matrix of JuMP variables, and several millions of constraints in those. In the naive formulation the size is what obstructs solving the problem in reasonable time; I decided to play smart…

---

## [Announcement: Fast Spherical Harmonics](https://discourse.julialang.org/t/announcement-fast-spherical-harmonics/3810)

<div class="topic-metadata">

**Author:** [@MikaelSlevinsky](https://discourse.julialang.org/u/MikaelSlevinsky)\
**Replies:** 0\
**Last updated:** [May 19, 2017, 4:29pm UTC](https://discourse.julialang.org/t/announcement-fast-spherical-harmonics/3810 "2017-05-19T16:29:19Z")

</div>

I’m excited to announce a major release of FastTransforms.jl introducing the first fast and backward stable transform between spherical harmonic expansions and bivariate Fourier series! And it’s in Julia first. Convert …

---

## [Correlation coefficient](https://discourse.julialang.org/t/correlation-coefficient/3966)

<div class="topic-metadata">

**Author:** [@acad2](https://discourse.julialang.org/u/acad2)\
**Replies:** 1\
**Last updated:** [May 29, 2017, 4:01am UTC](https://discourse.julialang.org/t/correlation-coefficient/3966 "2017-05-29T04:01:08Z")

</div>

The function for Pearson correlation coefficient is cor. Isn’t it a good idea to make it (something like) correlation? Otherwise, it looks like cryptic function names in Matlab.

---

## [ISC on fMRI data and related problems](https://discourse.julialang.org/t/isc-on-fmri-data-and-related-problems/3945)

<div class="topic-metadata">

**Author:** [@AShedko](https://discourse.julialang.org/u/AShedko)\
**Replies:** 0\
**Last updated:** [May 26, 2017, 8:09pm UTC](https://discourse.julialang.org/t/isc-on-fmri-data-and-related-problems/3945 "2017-05-26T20:09:04Z")

</div>

ISC (inter-subject correlation) is a medical imaging method that gives you the segments of the brain that behave similarly when under similar stimuli. I am essentially calculating a voxelwise correlation of a bunch of 5…

---

## [Proposed overhaul of DataStreams](https://discourse.julialang.org/t/proposed-overhaul-of-datastreams/3677)

<div class="topic-metadata">

**Author:** [@ExpandingMan](https://discourse.julialang.org/u/ExpandingMan)\
**Replies:** 7\
**Last updated:** [May 25, 2017, 8:43pm UTC](https://discourse.julialang.org/t/proposed-overhaul-of-datastreams/3677 "2017-05-25T20:43:14Z")

</div>

The DataStreams package is a great idea, and I’ve very much embraced it, but I think most agree it’s time for a major overhaul as it’s confusing to users and doesn’t cover enough use cases. I’ve written my ideas out in …

---

## [Union type data frame implementation?](https://discourse.julialang.org/t/union-type-data-frame-implementation/3925)

<div class="topic-metadata">

**Author:** [@ExpandingMan](https://discourse.julialang.org/u/ExpandingMan)\
**Replies:** 4\
**Last updated:** [May 25, 2017, 7:24pm UTC](https://discourse.julialang.org/t/union-type-data-frame-implementation/3925 "2017-05-25T19:24:44Z")

</div>

I’m a little hesitant to ask mildly terrified of asking, but has any thought been given to writing a dataframe implementation using union types, as we’ve been told that updates in the handling of union types will render …

---

## [TimeArray -\> {Regular,Irregular}TimeArray](https://discourse.julialang.org/t/timearray-regular-irregular-timearray/3919)

<div class="topic-metadata">

**Author:** [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)\
**Replies:** 0\
**Last updated:** [May 25, 2017, 6:50am UTC](https://discourse.julialang.org/t/timearray-regular-irregular-timearray/3919 "2017-05-25T06:50:05Z")

</div>

TimeArray is the type underlying JuliaStats/TimeSeries. I need a slightly finer distinction and the ability to dispatch over each, RegularTimeArray (where deltaTime is constant) and IrregularTimeArray (where deltaTime i…

---

## [Infeasibility Testing](https://discourse.julialang.org/t/infeasibility-testing/3910)

<div class="topic-metadata">

**Author:** [@gopal2017](https://discourse.julialang.org/u/gopal2017)\
**Replies:** 3\
**Last updated:** [May 24, 2017, 6:47pm UTC](https://discourse.julialang.org/t/infeasibility-testing/3910 "2017-05-24T18:47:07Z")

</div>

In CPLEX we have option to detect conflicting equations and/ check infeasibility of the model,if any. I am using Clp solver. Is there any option to do aforementioned task?

---

## [Change of variable and constraint name](https://discourse.julialang.org/t/change-of-variable-and-constraint-name/3860)

<div class="topic-metadata">

**Author:** [@gopal2017](https://discourse.julialang.org/u/gopal2017)\
**Replies:** 5\
**Last updated:** [May 24, 2017, 1:19pm UTC](https://discourse.julialang.org/t/change-of-variable-and-constraint-name/3860 "2017-05-24T13:19:19Z")

</div>

Please let me know the way to change variable name and constraint name. We usually do it in CPLEX to change default name of variables and constraints to make it more meaningful and to give better understanding of .lp fil…

---

## [Rotated cone constraint, how to include it?](https://discourse.julialang.org/t/rotated-cone-constraint-how-to-include-it/3879)

<div class="topic-metadata">

**Author:** [@rayset](https://discourse.julialang.org/u/rayset)\
**Replies:** 2\
**Last updated:** [May 24, 2017, 12:13pm UTC](https://discourse.julialang.org/t/rotated-cone-constraint-how-to-include-it/3879 "2017-05-24T12:13:01Z")

</div>

I’ve been trying for a few days to add the following constraint in jump: @NLconstraint(mod, R\[i,j,h\]^2 + T\[i,j,h\]^2 - 2\*u\_ijk\[i,i,j,h\]\*u\_ijk\[j,j,i,h\]\<=0) I tried every academic solver, but none is able to recognize t…

---

## [Meaning of tetEdgeCrnrs and tetTri in marching\_tetrahedra.jl of Meshing.jl](https://discourse.julialang.org/t/meaning-of-tetedgecrnrs-and-tettri-in-marching-tetrahedra-jl-of-meshing-jl/3903)

<div class="topic-metadata">

**Author:** [@mohamed82008](https://discourse.julialang.org/u/mohamed82008)\
**Replies:** 0\
**Last updated:** [May 24, 2017, 10:04am UTC](https://discourse.julialang.org/t/meaning-of-tetedgecrnrs-and-tettri-in-marching-tetrahedra-jl-of-meshing-jl/3903 "2017-05-24T10:04:10Z")

</div>

The following is part of the source code of marching\_tetrahedra.jl in the Meshing.jl module. The tetEdgeCrnrs and tetTri fields of the VoxelIndices immutable don’t really make sense to me, so I would appreciate the help…

---

## [Can VTK.jl load and save vtk and pvd files?](https://discourse.julialang.org/t/can-vtk-jl-load-and-save-vtk-and-pvd-files/3901)

<div class="topic-metadata">

**Author:** [@mohamed82008](https://discourse.julialang.org/u/mohamed82008)\
**Replies:** 4\
**Last updated:** [May 24, 2017, 9:31am UTC](https://discourse.julialang.org/t/can-vtk-jl-load-and-save-vtk-and-pvd-files/3901 "2017-05-24T09:31:14Z")

</div>

I am trying to figure out the mesh importing and exporting capabilities of Julia. I came across VTK.jl but but it was hardly documented, so I wonder, is it possible to use VTK.jl to load and save vtk or pvd file formats? …

---

## [Visualizing a 3D Vectorfield](https://discourse.julialang.org/t/visualizing-a-3d-vectorfield/3852)

<div class="topic-metadata">

**Author:** [@steinhagelvoll](https://discourse.julialang.org/u/steinhagelvoll)\
**Replies:** 7\
**Last updated:** [May 24, 2017, 6:38am UTC](https://discourse.julialang.org/t/visualizing-a-3d-vectorfield/3852 "2017-05-24T06:38:56Z")

</div>

I am trying to visualize a 3D Vectorfield like this: Is there any Julia library capable of creating plots like these?

---

## [Special functions , associated Legendre type 3](https://discourse.julialang.org/t/special-functions-associated-legendre-type-3/2163)

<div class="topic-metadata">

**Author:** [@elaine](https://discourse.julialang.org/u/elaine)\
**Replies:** 15\
**Last updated:** [May 23, 2017, 12:51am UTC](https://discourse.julialang.org/t/special-functions-associated-legendre-type-3/2163 "2017-05-23T00:51:33Z")

</div>

I have some special functions. I would like to deposit them into someone’s existing / new projects. An example: function mylegenp3(n,m,z)# n,m integers , z \> 1,associated Legendre v=(z\*z - big(1.))^(-m\*big(1)/2) …

---

## [Pipe to CSV.Source](https://discourse.julialang.org/t/pipe-to-csv-source/3764)

<div class="topic-metadata">

**Author:** [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Replies:** 4\
**Last updated:** [May 22, 2017, 10:23pm UTC](https://discourse.julialang.org/t/pipe-to-csv-source/3764 "2017-05-22T22:23:17Z")

</div>

I have a gzip-compressed CSV file in which uses commas for the decimal mark. I can uncompress and then use tr on the command line, but I would prefer doing that using a pipe from Julia. I tried using CSV using DataStrea…

---

## [A Suggestion to Integrate GLVisualize and Paraview](https://discourse.julialang.org/t/a-suggestion-to-integrate-glvisualize-and-paraview/3844)

<div class="topic-metadata">

**Author:** [@mohamed82008](https://discourse.julialang.org/u/mohamed82008)\
**Replies:** 4\
**Last updated:** [May 22, 2017, 6:27pm UTC](https://discourse.julialang.org/t/a-suggestion-to-integrate-glvisualize-and-paraview/3844 "2017-05-22T18:27:04Z")

</div>

I am a fan of Paraview and a student of GLVisualize. In my usecase, I am trying to make and visualize mesh node data, including scalar and vector fields defined over those nodes. Paraview does an excellent job at that u…

---

## [Generating strongly correlated data for numerical experiments](https://discourse.julialang.org/t/generating-strongly-correlated-data-for-numerical-experiments/3842)

<div class="topic-metadata">

**Author:** [@varun7rs](https://discourse.julialang.org/u/varun7rs)\
**Replies:** 4\
**Last updated:** [May 22, 2017, 11:10am UTC](https://discourse.julialang.org/t/generating-strongly-correlated-data-for-numerical-experiments/3842 "2017-05-22T11:10:38Z")

</div>

Since real-life traffic traces are not readily available, for my simulations, I generate traffic traces as follows: trace = \[\] nom = sample(collect(0.5:0.2,0.9), WeightVec(\[0.3,0.4,0.3\])) for i=1:100 push!(trace, nom …

---

## [JuMP variable definition](https://discourse.julialang.org/t/jump-variable-definition/920)

<div class="topic-metadata">

**Author:** [@ashefa](https://discourse.julialang.org/u/ashefa)\
**Replies:** 12\
**Last updated:** [May 20, 2017, 4:13pm UTC](https://discourse.julialang.org/t/jump-variable-definition/920 "2017-05-20T16:13:22Z")

</div>

how i can defined different bounds or fixed values to elements of a vector variable?

---

## [Syntax Error while running MPC with Ipopt](https://discourse.julialang.org/t/syntax-error-while-running-mpc-with-ipopt/3817)

<div class="topic-metadata">

**Author:** [@Angshuman\_Goswami](https://discourse.julialang.org/u/Angshuman_Goswami)\
**Replies:** 1\
**Last updated:** [May 20, 2017, 12:26pm UTC](https://discourse.julialang.org/t/syntax-error-while-running-mpc-with-ipopt/3817 "2017-05-20T12:26:26Z")

</div>

I am working with the simulator with a 3DOF-bicycle model. I am having a problem when I use the dynamic model in the MPC. When I am using the kinematic model, it works. I have uploaded the files here. (https://github.co…

---

## [Sample random matrix](https://discourse.julialang.org/t/sample-random-matrix/3789)

<div class="topic-metadata">

**Author:** [@jacobcvt12](https://discourse.julialang.org/u/jacobcvt12)\
**Replies:** 3\
**Last updated:** [May 18, 2017, 3:29pm UTC](https://discourse.julialang.org/t/sample-random-matrix/3789 "2017-05-18T15:29:18Z")

</div>

Hi all, I’m trying to sample a random matrix, where each element is independent. For example, if I have a matrix of means M = \[1. 10.; 100. 1000.\] and I want to generate data, where each element is sampled as an expon…

---

## [Specifying the coefficients for a 2D polynomial in ApproxFun.jl](https://discourse.julialang.org/t/specifying-the-coefficients-for-a-2d-polynomial-in-approxfun-jl/3782)

<div class="topic-metadata">

**Author:** [@JackDevine](https://discourse.julialang.org/u/JackDevine)\
**Replies:** 4\
**Last updated:** [May 18, 2017, 8:13pm UTC](https://discourse.julialang.org/t/specifying-the-coefficients-for-a-2d-polynomial-in-approxfun-jl/3782 "2017-05-18T20:13:50Z")

</div>

I am trying to understand how ApproxFun.jl constructs 2D functions from their coefficients. In 1D, it all makes sense, for example: julia\> using ApproxFun julia\> f = Fun(Interval(-1, 1), \[1,2,3\]) Fun(Chebyshev(【-1.0,1.…

---

## [Violin plot interpolates too much](https://discourse.julialang.org/t/violin-plot-interpolates-too-much/3784)

<div class="topic-metadata">

**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 9\
**Last updated:** [May 18, 2017, 1:03pm UTC](https://discourse.julialang.org/t/violin-plot-interpolates-too-much/3784 "2017-05-18T13:03:04Z")

</div>

I am trying to draw a violin plot of forest structure (distribution of volumes by diameter class). The problem is that violin plot try to interpolate “too much” and draws too many waves: using DataFrames, Plots, StatPl…

---

## ["multivariate curve resolution"... a NMF using ALS?](https://discourse.julialang.org/t/multivariate-curve-resolution-a-nmf-using-als/3274)

<div class="topic-metadata">

**Author:** [@charlesll](https://discourse.julialang.org/u/charlesll)\
**Replies:** 1\
**Last updated:** [May 18, 2017, 7:02am UTC](https://discourse.julialang.org/t/multivariate-curve-resolution-a-nmf-using-als/3274 "2017-05-18T07:02:06Z")

</div>

Dear all, I am using Julia and the JuliaStats ecosystem together with SciKit-learn (thanks PyCall) to perform component analysis and blind-source separation in various Raman and also XAFS spectra of glasses with varying…

---

## [Asymmetric violin plot (different right/left series)](https://discourse.julialang.org/t/asymmetric-violin-plot-different-right-left-series/3770)

<div class="topic-metadata">

**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 2\
**Last updated:** [May 17, 2017, 9:42pm UTC](https://discourse.julialang.org/t/asymmetric-violin-plot-different-right-left-series/3770 "2017-05-17T21:42:19Z")

</div>

Hello, I am trying to obtain a violin plot with different series on the right and on the left. I have tried this code plying from the example in the doc, but I am unable to specify that one series should be on the left …

---

## [Speed up this code game](https://discourse.julialang.org/t/speed-up-this-code-game/3666)

<div class="topic-metadata">

**Author:** [@Glen](https://discourse.julialang.org/u/Glen)\
**Replies:** 13\
**Last updated:** [May 17, 2017, 3:37am UTC](https://discourse.julialang.org/t/speed-up-this-code-game/3666 "2017-05-17T03:37:45Z")

</div>

Hi, Brag points are up for grabs again. How can this code be made faster? using BenchmarkTools using Base.Test struct Point{X,Y} x::X y::Y end function integral\_squared(v::Vector{Point{X,Y}}) where {X,Y} …

---

## [Custom DataFrame column sort order](https://discourse.julialang.org/t/custom-dataframe-column-sort-order/3716)

<div class="topic-metadata">

**Author:** [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)\
**Replies:** 5\
**Last updated:** [May 16, 2017, 1:41pm UTC](https://discourse.julialang.org/t/custom-dataframe-column-sort-order/3716 "2017-05-16T13:41:22Z")

</div>

Is it possible to sort a DataFrame column based on custom sort order, e.g. df = DataFrame(col1= \['a','b','c'\], col2 = \[1,2,3\]) sort!(df, col1=custom\_order('a','c','b'))

---

## [Thinking through distance matrix calculation](https://discourse.julialang.org/t/thinking-through-distance-matrix-calculation/3725)

<div class="topic-metadata">

**Author:** [@randyzwitch](https://discourse.julialang.org/u/randyzwitch)\
**Replies:** 5\
**Last updated:** [May 16, 2017, 1:35pm UTC](https://discourse.julialang.org/t/thinking-through-distance-matrix-calculation/3725 "2017-05-16T13:35:27Z")

</div>

I got a workstation with 2 P5000 cards in it and I want to check out CUDAnative.jl (or other options people can suggest). I understand why GPUs can produce faster results for brute force calculations, but this is my firs…

---

## [Gadfly - plot with several graphs, suitable for publications](https://discourse.julialang.org/t/gadfly-plot-with-several-graphs-suitable-for-publications/3718)

<div class="topic-metadata">

**Author:** [@lanaperisa](https://discourse.julialang.org/u/lanaperisa)\
**Replies:** 2\
**Last updated:** [May 15, 2017, 5:58pm UTC](https://discourse.julialang.org/t/gadfly-plot-with-several-graphs-suitable-for-publications/3718 "2017-05-15T17:58:54Z")

</div>

I’ve lost quite a lot of time to figure our how to include different line styles on graphs with different colors, so it is suitable for black&white publications. After several switching from package to package I’ve decid…

---

## [A question on extrapolation with Interpolations.jl](https://discourse.julialang.org/t/a-question-on-extrapolation-with-interpolations-jl/3669)

<div class="topic-metadata">

**Author:** [@JackDevine](https://discourse.julialang.org/u/JackDevine)\
**Replies:** 15\
**Last updated:** [May 15, 2017, 9:20am UTC](https://discourse.julialang.org/t/a-question-on-extrapolation-with-interpolations-jl/3669 "2017-05-15T09:20:37Z")

</div>

Say that I make an array that I want to do extrapolation on: using Interpolations a = \[1,2,3,4\] a = interpolate!(a, BSpline(Linear()), OnGrid()) a = extrapolate(a, 3) Then a\[0\] = 3 and likewise for any index outside of…

---

## [Significand of IEEE float as an integer](https://discourse.julialang.org/t/significand-of-ieee-float-as-an-integer/3698)

<div class="topic-metadata">

**Author:** [@fengyang.wang](https://discourse.julialang.org/u/fengyang.wang)\
**Replies:** 2\
**Last updated:** [May 14, 2017, 8:25pm UTC](https://discourse.julialang.org/t/significand-of-ieee-float-as-an-integer/3698 "2017-05-14T20:25:25Z")

</div>

I want a function like frexp, but that returns an integer (of the same size of the floating point) and an exponent. Currently I have tried the following implementation: julia\> inexp(x::T) where T \<: Base.Math.IEEEFloat …

[Previous page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=559)

[Next page](https://discourse.julialang.org/c/domain/10.md?no_subcategories=false&page=561)